Such launching and recovery devices have been described in the prior art in patents to Rockwood (U.S. Pat. No. 5,245,940) and Montgomery (U.S. Pat. Nos. 4,983,067 & 5,090,842). By and large, each of those arrangements incorporate an elongated vertical post having separable upper and lower portions, with the lower portion having a lower end driven into the ground bottom beneath the water adjacent a dock or seawall and an upper end which is disposed at the upper edge of this dock or seawall, a connection between the upper end of the lower post portion and the dock or seawall, a winch mounted on an upper end of the upper post portion and rotatable therewith, a cradle for supporting the watercraft cantilevered on the post and extending laterally from it to slide along the post and a hoist extending between the winch and cradle for raising and lowering the cradle during operation. Each of those inventions further utilize a roller construction between the post and cradle for supporting the cradle on the post during vertical movement.
One skilled in the art, in reviewing such patents would first of all note that the roller constructions employed are quite complex. In Rockwood, for example, there are what are termed "load supporting rollers", "side rollers", and several other types of rollers required for the described operation, but not given any descriptive name. While the rollers there discussed may very well be sufficient in supporting a cradle when moving jet skis of the order of 250-400 pounds, one skilled in the art would very well understand that different roller constructions and sizes would very well be needed if the cradle were being used to raise and lower larger watercraft--whether they be 800 pounds, 1,000 pounds, 1,200 pounds, or whatever. Although one way of dealing with such situations might very well involve increasing the dimensions of the elongated vertical post there utilized to increase stability, that would still not be the complete story as different rollers of increased bearing capacity would still be required, even if the large numbers of rollers employed were not susceptible to breakdown or failure during repeated use; obviously, the greater the number of rollers and the complexity involved, the greater the propensity for something to go wrong. Similarly, with the Montgomery designs, changes are required, of necessity, in the roller construction as added watercraft weights are encountered, else the stability of the provided support will suffer if not lead to failure.